1. Field of the Invention
The present invention relates to a voice communication apparatus which is used in such a portable mobile communication system as a car radio telephone system or a cordless radio telephone system and which is based on a voice operated transmitter (VOX) for voice communication.
2. Description of the Related Art
Such a portable voice communication apparatus as a portable radio telephone set or a cordless radio telephone set usually uses a battery as its power source. In this connection, the miniaturization of such a battery has been demanded for the purpose of making smaller in the size and weight of the portable voice communication apparatus. For miniaturizing the battery, it is important not only to improve the battery itself but also to lower the overall power consumption of the portable voice communication apparatus.
As one of methods for effectively reducing the power consumption of such a portable voice communication apparatus, there has been recently considered a so-called VOX-based method in which a transmission circuit is operated only for a period of time during which an operator utters in its speech mode to transmit its voice signal while the operation of the transmission circuit is stopped for voice wait durations corresponding to operator's pauses. When this VOX is utilized, the power consumption of the transmission circuit can be reduced by an amount corresponding to the stopped operation or voice-absence periods of the circuit, when compared to a case where the transmission circuit is always activated throughout the speech mode.
However, according to the prior art apparatus, when an operator starts to input voice from voiceless state, due to the delay processing of preventing any erroneous detecting operation, the detection of the voice is delayed by several milliseconds with respect to a time point at which the voice signal is actually inputted. As a result, the prior art apparatus has been defective in that a head part of the voice data preceding a voice detection point is missing in the transmitted voice data so that the signal receiver cannot reproduce the missing head part of the voice data and thus the quality of the reproduced voice data is extremely deteriorated.